Artificial lighting is an essential element of modern life. How to achieve ideal effects of artificial lighting has been a hot research topic. Many factors are to be considered for optimizing artificial lighting, such as efficiency of energy saving of the lighting solution, safety of an environment under lighting, aesthetics of illuminated objects or scenes, and animal's physiological or psychological reactions to artificial lighting, etc. For example, some studies show that long-term exposure under inappropriate illumination spectra could incur human health problems, such as the seasonal affective disorder. Research on human mesopic vision also suggests that in mesopic vision, spectral responses of human eyes bias towards shorter wavelengths. Thus, a satisfying luminous efficacy under photopic vision conditions may not be sufficient or as satisfactory under mesopic vision conditions.
Traditional evaluation on artificial light sources typically focuses on parameters such as luminous efficacy, color rendering and color temperature. However, as artificial lighting needs in modern life diversify and with advancement in research fields such as mesopic vision and non-visual biological effect, the traditional parameters quickly become insufficient to account for efficiency, comfort, safety, health concerns and various other considerations of artificial lighting. Thus, there exists a need in the field for a new artificial lighting solution capable of solving the above problems.